The present invention relates to a projection-type image display apparatus, for modulating light intensity of lights irradiated from an illumination optic system, through liquid crystal image display elements (i.e., panels) for use of lights of R, G and B, in particular, applying polarization effect therein, thereby forming an optic image, and projecting said optic image upon a screen through a projection optic system.
Conventionally, the projection-type image display apparatus was already known by a name, such as, a liquid crystal projector or the like, for example, i.e., containing an optical unit, as well as, an electric source circuit and/or a video driver circuit within a housing thereof, for projecting the optic image that is formed through modulating the light intensity upon the lights from a light source, with applying polarization effect thereto, so as to vary the density for each of pixels, depending on an image signal through light valve elements for use of R-, G- and B-lights, and thereby projecting the said optic image formed onto the screen or the like, by means of a projection lens. Further, at present, as such the light valve element mentioned above is also widely known and practically used, for example, so-called a transmission or a transparent-type liquid crystal panel, or a reflection-type liquid crystal panel, etc.
As the optic unit of such the projection-type image display etc., for example, because of the reasons that the conversion efficiency there of is high and that lights can be easily obtained therewith, being very similar to that irradiated from a point-like light source. However, with such the liquid crystal projector, it is tried to obtain high-brightness, as well as, high-definition, accompanying with large-sizing of a display screen thereof, i.e., adopting a high-output lamp therein (for example, the metal halide lamp having an electric power, being equal to 250 W or larger than that), and for this reason, ill-influences are exerted on the characteristics of the liquid crystal panels, by the heats generating from such the light radiation source of high output, and further the heat-generation of the liquid crystal panels due to irradiation of strong lights from that light radiation source.
Then, conventionally, within such the projector, for the purpose of preventing various portions of the apparatus including the liquid crystal panel (in particular, a lamp and a controller portion thereof) from increasing of temperature, i.e., protecting them from the ill-influences thereof, there is provided a fan for use of air cooling, and thereby introducing/circulating cooling air from an outside of the apparatus into an inside of a housing thereof. Further, as is already known in Japanese Patent Laying-Open No. 2004-354795 (2004), an attempt is made for cooling down the cross dichroic prisms including the liquid crystal panels, which is installed within the housing while being mounted on an attachment member having a cooling fin on one-side surface thereof, thereby to obtain cooling through a cooling air current within that housing.
On the other hand, with the reflection-type liquid crystal panels or the transparent-type liquid crystal panels, to be applied as the light intensity modulating elements within such the optic unit, also demand is made remarkably for small-sizing, as well as, for low-costs thereof, in recent years, and therefore the strong lights emitted from the light radiation source are irradiated upon the liquid crystal panels, each having a smaller surface area thereof. For this reason, the heat generation on the liquid crystal panel due to the light irradiation comes up to be large much more, but on the contrary to that, it is difficult by any possibility, to suppress such the heat-generation on the liquid crystal panel as was mentioned above, fully by only means of the introduction and/or the circulation of cooling air into the inside of the apparatus by means of the air-cooling fan mentioned above.
Then, according to the present invention, by taking the drawbacks of the conventional arts mentioned above into the consideration thereof, i.e., an object thereof is to provide the practical structures of the optic unit, in particular, for enabling to achieve the optical performances desired, depending on necessity thereof, dissolving those deteriorations in performances that are caused due to the heat generation mentioned above, within the projection-type image display apparatus, representatively, such as, the liquid crystal projector, for example, upon which requirements are made strongly for the high-definition, as well as the high-brightness thereof, and in other words, an improved projection-type image display apparatus.
Namely, according to the present invention, first of all, there is provided a projection-type image display apparatus, comprising the followings in a housing thereof: a light source; an illumination optic system; penetration-type image display elements for R-, G- and B-lights; an optical synthesizing means, and a projection lens, wherein the R-light penetration-type image display element, the G-light penetration-type image display element and the B-light penetration-type image display element are attached on surfaces different from each other of the said cross dichroic prisms, for building up the optical synthesizing means, onto which the display elements are attached, in one body, so that the said cross dichroic prisms attached with the display elements thereon can be attached, detachably, while opposing to a surface different from those, on which the display elements are attached, to an incident surface of the projection lens.
Further, according to the present invention, there is also provided a projection-type image display apparatus, comprising the followings in a housing thereof: a light source; an illumination optic system; reflection-type image display elements for R-, G- and B-lights; an optical synthesizing means, and a projection lens, wherein the R-light penetration-type image display element, the G-light penetration-type image display element and the B-light penetration-type image display element are attached with the said cross dichroic prisms for building up the optical synthesizing means, in one body, on optical paths opposing to surfaces thereof different from each other, so that the said cross dichroic prisms attached with the display elements thereon can be attached, detachably, while opposing to a surface different from those, on which the display elements are attached, to an incident surface of the projection lens.